The invention relates to a device for emitting acoustic waves by implosion, particularly adapted to marine seismic prospection.
Known devices for emitting acoustic waves by implosion comprise two members movable with respect to each other, defining with at least one flexible membrane interconnecting them at their periphery, a tight enclosure inside which prevails a pressure lower than the external pressure and, preferably, a very small pressure, associated to means for moving the movable members away from each other, said means comprising a cylinder integral with one of said movable members and a piston slidably mounted therein and adapted to push the other movable member upon actuation of a hydraulic system, up to a spaced apart position where it is maintained intermittently by locking means. The fluid compressed by the hydraulic system acts on the piston either directly or through a movable mechanical part taking its bearing intermittently on the piston and driving it toward the spaced apart position of the movable members.
The hydraulic feeding system of the device comprises means for pressurizing a fluid, e.g. oil, and operated in closed loop. Since the emitting device may have to be towed by a ship while immersed, over a relatively long distance, the total length of the lines for feeding the device with pressurized fluid and returning the latter to the ship may be very substantial.